You see the key isn't to cover just everything, then it's not assistance. The key is to think about what is needed on a weekly basis to support the main exercises. That's why I leave it open as a secondary exercise, that could be whatever is needed.

I sometimes do Front Squats, in fact I do them a lot. So that is why I tend to leave it stated as "Secondary exercise" rather than prescribe anything more specific.

Let the speed sessions guide your week, fill in with whatever is needed.